The invention relates generally to methods of replicating data stored in a database on a server computer and in particular to replicating the data to a cross-domain second server.
Businesses commonly use databases to store large amounts of data for easy access and manipulation by various people within the business entity. In some cases people outside the business may also be given access to one or more databases. While maintaining a single centralized database has the advantage of avoiding inconsistencies which might occur with multiple copies, there is often a need to replicate the data stored in a database on one server computer to a second server computer. Where only one copy of the database exists, the system may appear slow when multiple users attempt to process such cross-server transactions. If the server having the single copy becomes unavailable, then the entire system may become unavailable. Today""s business organizations, especially those with multiple locations often have server computers located at the various locations interconnected via a communicating network.
A user with access to one server may need to perform a transaction involving data in a database located on another server. Whether the second server is located at a remote location or at the same location as the first server, access controls commonly used in business for security purposes may either allow or prevent such a transaction from occurring.
For these reasons and others, there is often a need to replicate a database from one server to another. That is a copy of each data item stored in a database on one server may also reside on a second server. By replicating the data across multiple servers, a level of fault tolerance is achieved. In addition, the response time for transactions run on a local copy of the database is usually much faster.
Various strategies have been developed for maintaining the multiple copies of data to insure that transactions run on one copy are accurately reflected in other copies throughout the system. Cheng et al. in U.S. Pat. No. 5,884,324 use a database table and data replication period to reconstruct changes made to a database and transmit the changes to a remote server. Gostanian et al. in U.S. Pat. No. 5,781,910 describe using coordination protocols which govern the execution of the transactions to assure consistent data replication across the system. Gehani et al, in U.S. Pat. No. 5,765,171 use a database version vector to keep track of the updates to data items in the copies. During replication the version vectors are compared to determine if replication is necessary. In U.S. Pat. No. 5,802,062, Gehani et al. use a token passing system to prevent conflicts and eliminate a need for coordination of execution. Olds et al. in U.S. Pat. No. 5,832,487 describe a method of identifying replicas with tuned-name identifiers which provides improved synchronization over other existing methods. Hacherl et al. in U.S. Pat. No. 5,832,225 uses a knowledge consistency checker to enforce replication as efficiently as possible so that each change is transmitted only once in a single direction over interserver links which are expensive.
All of these strategies for maintaining copies require some method of replicating some or all of the data in a database on one server to another server.
Unfortunately, some security methods such as provided by the LOTUS NOTES(copyright) product (LOTUS NOTES is a registered trademark of Lotus Development Corp of Cambridge, Mass.) require that two servers reside in the same domain for normal replication of a database to proceed. For cross-domain replication to occur, a cross-certificate must be issued by a source server to a destination server. Most organizations do not permit their server to issue cross-certificates to other servers because of the potential for compromised security, or for other business reasons. A system administrator who maintains a server is therefore prevented from using the benefits of replication of a database as described above. In accordance with the teachings of the present invention, there is defined an improved and unique method for performing such a replication.
It is believed that such a method would constitute a significant advancement in the art whether used with one of the above strategies or not.
It is therefore a principal object of the present invention to provide a method of replicating data stored in a database on a first server to a second database on a second server.
It is a another object to provide such a method wherein the second server resides in a different domain from the first server.
It is a further object to provide such a method which is implemented in a relatively inexpensive and rapidly running manner.
These and other objects are attained in accordance with one embodiment of the invention wherein there is provided a method of replicating records in a source database on a first server to a second database on a cross-domain second server, comprising the steps of, forming a devoted client having access to the first and second servers, creating a generic agent manager database on the devoted client having one field, one form, one document, and one view, creating an intermediary agent in the generic agent manager database, and running the intermediary agent against the source database on the first server to replicate the records to the second database on the second server.